Help me with science timed homework

The use of dna as evidence in criminal investigations became possible because of the

The oxidizing agent our bodies use to obtain energy from food is oxygen (from the air). if you breathe 15 times a minute (at rest), taking in and exhaling 0.5 l of air with each breath, what volume of air do you breathe each day? air is 21% oxygen by volume. what volume of oxygen do you breathe each day?

If your client can successfully complete two or more repetitions above the desired repetition range in the last set in two consecutive workouts for any given exercise, the load should be depending on your client's current physical abilities. increased by 1-5% increased by 2-10% increased by 5-15% increased by 10-20% none of these